November 12, 2018
Let’s be real, we all love fieldwork. It feels great to take a break from the repetitive days of grinding in the office and go outside to get your hands dirty.
In mid-October I was fortunate to travel to the Mojave Desert and participate in the Mojave Broadband Seismic Experiment. The project seeks to understand how strain is distributed across the Eastern California Shear Zone and how the lithosphere evolved since the Laramide Orogeny. Led by PIs Thorsten Becker, Whitney Behr, and Vera Schulte-Pelkum, the experiment is comprised of 19 broadband seismometers deployed 2 km apart on a single 40 km-long line. The instruments were deployed in Spring 2018 and are set to record seismic events from all over the world for two years. Robert Porritt (UTIG Postdoctoral Fellow working with Thorsten) recruited Kelly Olsen (PhD ‘21), Simone Puel (PhD ‘22), and me (PhD ‘21) to help service the seismometers, which consists of downloading data, making sure everything is working properly, and installing protection to the GPS and sensor cables.
Overview maps showing location of the seismic instruments in Mojave Desert with regional faults.
Our basecamp was the California Inn in the thriving metropolis of Barstow, CA. The seismic line was located a 1-hour drive east of Barstow near a “town” called Ludlow, which only had a gas station, a Dairy Queen, a small diner, and a Motel 6. Rob described the motel in Ludlow as the “sketchiest thing I’ve ever seen”, so we were all pretty happy to exchange a slightly longer drive for tasty restaurants and comfort in Barstow. Every day we split into two teams with the goal of servicing three stations per team. We quickly learned this is easier said than done in the Mojave Desert! The area is extremely desolate – no roads, no trails, and no signs of life, anywhere. To get close to some stations we drove up dry river channels and through desert shrubs (sorry rental car company). Other stations were located on Mojave National Preserve, so we just had to pull over on I-40 and crawl under barbed wire fences.
Typical Mojave Desert landscape view from instrument K.
The Mojave landscape is breathtaking. The red dirt and basalt colluvium made it feel like we were doing fieldwork on Mars. I am very thankful that it wasn’t summertime when temperatures are commonly 125°F. The geology was astonishing, and I was thrilled to see complex folds and volcanic flows, which was a nice break from the carbonates in Austin. Volcanic rocks dominate the desert – basalt, andesite, and rhyolite flows, lapilli, ignimbrites, and pumices. We also saw mountains of granite, schist, and gneiss, some volcanic breccias and arkose sandstones. Seeing cool rocks was a real treat for me and brought me back to my undergrad days as a geologist. Every desert shrub tried to kill us as we scrambled across this beautiful landscape; we all bled a small sacrifice to the Mojave.
Folds in schists, gneiss, and volcanic lapilli? (top right).
Sweet contact between orthogneiss and biotite schist.
At each station, we used a Bluetooth app to connect with the instrument and receive information, such as its current status, temperature, GPS clock, and the amount of data recorded. We also used the app to make sure the three sensor components were properly working and responding to ground motion (yes, we jumped on the ground like little kids). While downloading data onto our laptop, we installed a blue “fire hose” type material around the sensor cable and then buried it for protection against inquisitive desert critters. Lastly, to secure the GPS and solar panel cables, we wrapped them with $0.25 foam pool noodles (Kelly’s brilliant idea). A quick check to make sure everything was working fine, and we were off to the next station.
(Top left): A content seismometer. (Top right): Analog to digital converter stores data. (Bottom left): Rob digging up the seismometer to change the sensor cable. (Bottom right): Installing the blue fire hose to protect the sensor cable.
Beautiful views at stations K (top left), S (bottom left), B (top right), and J (bottom right – check out the killer folds in the background!).
All in all, our mission was a success, collecting quality seismic data from 18 of 19 stations for analyses back in Austin. Two stations had a severed GPS cable, one had a chewed sensor cable, and one was dead from losing connection with its solar panels. We brought spare cables to replace the damaged ones, and the new fire hose and pool noodle protection should ensure the stations happily record seismic arrivals until the next service run.
Chilling on some coarse granite at station S (Budweiser Springs).
After completing service on all 19 stations, we explored lava tubes at Pisgah Crater, a young (~22 Ka) cinder-cone volcano. I was surprised to find a road that allowed us to drive up to the rim of the crater! Watching the sunset on fresh basalt flows was a great way to end our time in the Mojave Desert. Before we flew back to Austin, we also spent a few hours relaxing at Santa Monica and Venice Beach. After hiking over 75 km through rough desert terrain for six days in tennis shoes, I was happy to dip my feet in the cold Pacific #SendItForScience.
Hanging out on top of Pisgah Crater. Photo credit: Simone.
Hook ‘Em Horns inside a young lava tube.
Relaxing in Venice Beach to celebrate after fieldwork. Photo credit: Simone.
This experience taught me that sometimes the best fieldwork does not have to be associated with your personal research. Even though I may not get involved with the analyses of these data, it was an extremely rewarding experience to learn about broadband seismic instruments and the geology of the Mojave Desert region, and to grow relationships with friends and colleagues.
